Unexamined and first publication DE 10 2012 103 378 A1 discloses a conveying device having a linear-motor drive. The known conveying device comprises a movable carriage and an encircling track rail which is disposed so as to be locationally fixed, for guiding the carriage. The carriage has a plurality of track rollers which bear on track faces of the track rail which are disposed in various planes and during movement of the carriage roll on the track faces.
On account of comparatively intense dynamic friction which arises during curved travel, heavy wear may arise. The reason therefor inter alia is the so-called wide-tire effect, which will be explained in the following. The track roller passes through a tight radius, on account of which the two external edges of the track roller have different running speeds (the center of the track roller having the “correct” speed, the internal edge running too fast and the external edge running too slowly). This results in dynamic friction on the external edges and thus in significantly higher wear as compared with simple rolling friction.
A further reason for increased wear is to be seen in the position of the track rollers which are disposed so as to be behind one another in the direction of the track. Typically, such track rollers which are disposed behind one another are not conceived for curved travel. After all, on account of their geometry, the track rollers in curved travel do not run along the curved path but are urged to leave the curved path. One track roller would be urged to run out of the curve, and the other track roller would be urged to run into the curve. However, the track rollers are retained on the track and generate substantial friction. The latter requires a comparatively high force and causes very heavy wear in comparison to simple rolling on the straight track.